GiGaBiTe
Veteran Member
So I bought an I-INC 28" monitor from a junk yard a few months ago for $20, and it worked great for about a month before it developed a fault (or it already had the fault and took that long to rear its head.) I figure I'd post about the repair process I did to get it working again.
The fault which it eventually developed is it wouldn't turn on without having to mess with the power button, either by holding it for an extended period of time or rapidly pressing it. I've experienced this problem before on other monitors, which I dreaded because it usually meant the power supply was failing. I disassembled it and right I was, the PSU was quite cooked:
https://i.imgur.com/YPcRmDs.jpg
The power supply board is the large board towards the bottom of the image. You can see the golden tinge covering most of the board, which is basically PCB, traces and solder that got far too hot. The culprit was most of the capacitors had gone high ESR or short and caused excessive current draw. I didn't take a picture of the other side, but you could see components all over had obviously been heavily stressed with dark brown circles around the legs. Recapping the power supply caused it to stop working completely, which was a bit irritating after dealing with cooked traces that would lift if you so much blew on them. I'm still not great at switching supply diagnostics, but I managed to get it partially working again (outputting unstable voltages on all rails) by finding some resistors which went dead short and replacing them. I assume that there were quite a few other insulted components that suddenly hated the clean power they were getting and died and didn't want to bother with it anymore, so I looked to another method, replacing the entire power board.
Since this monitor is so old, not many parts are available for it anymore. I eventually did find a used power board on Ebay from China for $75, but that was far out of budget, so I decided to try a repair I did on a 32" monitor over a year ago where I used one of those cheap chineseium 12v supplies and cascaded a buck and boost regulator off of it to get all of the power rails (in this case 24v and 5v.) This isn't an energy efficient monitor by any means (the backlight uses around 100W) so I opted to get a 300W 12v power supply, a 6A boost converter (for the 24v rail) and a 15A buck converter (for the 5v rail.) I salvaged the power connectors from the power supply and made an ugly protoboard power distribution board which seems to work. here's it all wired up and ready to be put back together:
https://i.imgur.com/rGS52OL.jpg
The 300W power supply is too large to fit inside the monitor, so I had to mount it externally on plastic standoffs:
https://i.imgur.com/4ji7QJV.jpg
It looks a bit tacky, but it works so far. My total cost was $15. It would have been $36, but the 300W PSU arrived damaged and the seller refunded the cost of the unit. I had to replace a transient filtering choke, bend the case back into shape and properly heatsink the mosfets to the case, since they weren't attached properly. I recommend you do this on any of these cheap units because the few I've bought all had these issues.
The fault which it eventually developed is it wouldn't turn on without having to mess with the power button, either by holding it for an extended period of time or rapidly pressing it. I've experienced this problem before on other monitors, which I dreaded because it usually meant the power supply was failing. I disassembled it and right I was, the PSU was quite cooked:
https://i.imgur.com/YPcRmDs.jpg
The power supply board is the large board towards the bottom of the image. You can see the golden tinge covering most of the board, which is basically PCB, traces and solder that got far too hot. The culprit was most of the capacitors had gone high ESR or short and caused excessive current draw. I didn't take a picture of the other side, but you could see components all over had obviously been heavily stressed with dark brown circles around the legs. Recapping the power supply caused it to stop working completely, which was a bit irritating after dealing with cooked traces that would lift if you so much blew on them. I'm still not great at switching supply diagnostics, but I managed to get it partially working again (outputting unstable voltages on all rails) by finding some resistors which went dead short and replacing them. I assume that there were quite a few other insulted components that suddenly hated the clean power they were getting and died and didn't want to bother with it anymore, so I looked to another method, replacing the entire power board.
Since this monitor is so old, not many parts are available for it anymore. I eventually did find a used power board on Ebay from China for $75, but that was far out of budget, so I decided to try a repair I did on a 32" monitor over a year ago where I used one of those cheap chineseium 12v supplies and cascaded a buck and boost regulator off of it to get all of the power rails (in this case 24v and 5v.) This isn't an energy efficient monitor by any means (the backlight uses around 100W) so I opted to get a 300W 12v power supply, a 6A boost converter (for the 24v rail) and a 15A buck converter (for the 5v rail.) I salvaged the power connectors from the power supply and made an ugly protoboard power distribution board which seems to work. here's it all wired up and ready to be put back together:
https://i.imgur.com/rGS52OL.jpg
The 300W power supply is too large to fit inside the monitor, so I had to mount it externally on plastic standoffs:
https://i.imgur.com/4ji7QJV.jpg
It looks a bit tacky, but it works so far. My total cost was $15. It would have been $36, but the 300W PSU arrived damaged and the seller refunded the cost of the unit. I had to replace a transient filtering choke, bend the case back into shape and properly heatsink the mosfets to the case, since they weren't attached properly. I recommend you do this on any of these cheap units because the few I've bought all had these issues.